(1) Field of the Invention
This invention relates to a method and apparatus for winding a coil on a toroidal core, and, more particularly, to a method and an apparatus suitable for use in winding a coil on a toroidal core of, for example, a magnetic head of a video tape recorder (VTR) or magnetic disc player by passing a wire through a minuscule aperture.
(2) Description of the Prior Art
An apparatus for winding a coil on a toroidal core is disclosed in Japanese Patent Unexamined Publication No. 186926/83, wherein a vacuum pipe located beneath a core window is actuated to draw by suction a wire positioned above the core window and pass the same through the core window, and then the vacuum pipe is moved downwardly to withdraw the wire and insert the same in an inlet, located beneath the core window, of an arcuate guide extending in a direction in which the wire is wound or from beneath to above the core window while a compressed air current is directed against the wire through a nozzle located on a side opposite the wire inlet side of the guide, to thereby feed the wire upwardly through the core window and wind the same on the toroidal core.
The problem encountered in this apparatus is that, since the wire is drawn by suction by a vacuum pipe and fed by compressed air while being held by the force of drawn air, difficulty is experienced in ensuring that the wire is positively passed through the core window and also in achieving increased speed of operation.
Another type of apparatus for winding a coil on a toroidal core is disclosed in U.S. Pat. No. 4,529,138 in which a wire is fed along an annular guide by rollers to wind the same on the toroidal core, and a portion of the wire is gripped and pulled by a gripper to achieve a winding of the wire on the toroidal core. This apparatus suffers the disadvantage that the mechanism for winding the wire on the core is complex, thwarting plans to obtain increased speed in operation for winding a wire. Additionally, the apparatus lacks means for avoiding buckling at a leading end portion of the wire and keeping the leading end portion of the wire from entering the inside of the wire guide when the wire has a low stiffness and the core window is small sized.